1. Field of the Invention
The present invention relates to an ink jet recording apparatus and more particularly to an ink jet recording apparatus having a wiping device for improving ink jetting condition of an ink jet head by wiping surplus ink remaining on an ink jetting plane of the ink jet head.
2. Description of Related Art
In general, printing operation is conducted in the ink jet recording apparatus by ejecting ink droplets from a nozzle plane of an ink jet head on a recording medium such as a print sheet. At this time of printing operation, the ink is left on the nozzle plane and if the ink is left alone directions of the ink droplets are deviated from the correct directions due to the remaining ink, thereby recording result is disturbed. In this way, in case that the surplus ink is left on the nozzle plane of the ink jet head, the ink jetting condition becomes inferior.
Therefore, in order to remove the remaining ink and recover the ink jetting condition normal, it is necessary to periodically clean the nozzle plane of the ink jet head. For this purpose, it is usual in the ink jet recording apparatus that it is installed out of recording area by the ink jet head a wiping mechanism in which the remaining ink on the nozzle plane is wiped and removed by a resilient wiper blade. Further, cleaning of the nozzle plane is periodically conducted by moving the ink jet head to a position opposite to the wiping mechanism.
By the way, after the wiping operation of the nozzle plane is conducted, the wiped ink is left on the wiper blade. If this condition (that is, the condition where the wiped ink is left on the wiper blade) is neglected as it is, it is possible that the wiped ink is reversely adhered to the ink jet head at the time of the next wiping operation, thereby it is conceivable that cleaning of the nozzle plane cannot be sufficiently done. To dissolve this problem, it is necessary to clean the wiper blade itself every wiping operation is conducted and to keep the clean condition for the next wiping operation.
Thus, in the ink jet recording apparatus, it is constructed so that an absorbing member made of urethane foam with good ink absorbing ability is arranged in the wiping mechanism and the wiped ink on the wiper blade is absorbed through the absorbing member by contacting the wiper blade with the absorbing member after the wiping operation, thereby the wiper blade is cleaned.
Here, the conventional wiping mechanism will be described according to FIG. 8. In FIG. 8, arrangement of the conventional absorbing member in the ink jet recording apparatus is disclosed. In FIG. 8, an absorbing member 74 is mounted on a carriage 72 in which an ink jet head 71 is installed. On the other hand, a wiper blade 75 is arranged at a side face of a holder 76 and is able to move in a direction indicated by an arrow U with the holder 76. When the carriage 72 is moved to recording area from non-recording area along a direction indicated by an arrow T, the holder 76 is moved ahead and a top of the wiper blade 75 is slightly projected in a moving plane of the nozzle of the ink jet head 71. In this state, if the carriage 72 is moved in the direction of the arrow T, the ink jet head 71 is first contacted with the wiper blade 75, thereby wiping operation is conducted, and thereafter the absorbing member 74 is contacted with the wiper blade 74, thereby cleaning of the wiper blade 75 is finished.
However, it is not always sufficient the above cleaning operation of the wiper blade 75 conducted by the absorbing member 74 in the conventional ink jet recording apparatus.
The reason is due to a relation existing between a first overlap width of the wiper blade 75 and the ink jet head 71 and a second overlap width of the wiper blade 75 and the absorbing member. That is to say, as shown in FIG. 9, in the conventional ink jet recording apparatus, the first overlap width A between the wiper blade 75 and the ink jet head 71 is wider than the second overlap width B between the wiper blade 75 and the absorbing member 74. Thus, it concludes that the ink remaining area of the wiper blade 75 where the wiped ink from the ink jet head 71 is left is not completely contacted with the absorbing member 74. Therefore, a part of the ink on the wiper blade 75 is left thereon without being absorbed by the absorbing member 74. In this way, since the next wiping operation is done while the ink is left on the wiper blade 75, cleaning of the ink jet head 71 cannot be sufficiently conducted by wiping operation.
Further, in case that the absorbing member 74 is mounted on the carriage 72 as shown in FIG. 8, the second overlap width B inevitably becomes narrower than the first overlap width A. Because, in order to avoid that the recording medium is contaminated by the absorbing member 74 which contacts with the recording medium while recording operation is done, it is necessary to inevitably mount the absorbing member 74 on the carriage 72 so that the top of the absorbing member 74 is slightly retracted from the nozzle plane of the ink jet head 71. Here, it is conceivable that the second overlap width B is made wider than the first overlap width A by moving more ahead the holder 76 when the wiper blade 75 contacts with the absorbing member 74, in comparison with a case that the wiper blade 74 contacts with the ink jet head 71. But, in this case, it will not be real since the mechanism for moving the holder 76 forward and backward and control thereof become very complicated.
Further, there exists an ink jet recording apparatus that the absorbing member is mounted on the main frame of the apparatus without mounting it on the carriage. But, the above first and the second overlap widths A and B are not considered in such ink jet recording apparatus.